Non destructive curve to mesh ?
It's possible when Surface> NURBS Curves or NURBS Circles are used. Add and select them all and join with Ctrl+J in Object Mode. Next go to Edit Mode and press A followed by F. In edit mode you can stretch your shape to the endpoints and edit it. Once done,you may use Alt+C to convert object to mesh. NB: the number of control points must be the same for each element.